A New Method of Synthesis of Nanosized Metal Oxide Powders

A new method of synthesis of nanosized metal oxide powders (Al₂O₃, MgO, ZnO) has been suggested. The method involves successive heat treatment at 350°С and then at 800°С of saturated solutions of the corresponding metal salts and sucrose. Physicochemical and technological properties of the synthesized materials have been determined.     

Passage of a Plane Shock Wave through the Region of a Glow Gas Discharge

Technical Physics - The interaction of a plane shock wave (M = 5) with an ionized plasma region formed before the arrival of a shock wave by a low-current glow gas discharge is considered...     

Determination of Elemental Sulfur in Bottom Sediments Using High-Performance Liquid Chromatography

A procedure for determining elemental sulfur in bottom sediments by microcolumn reversed-phase high-performance liquid chromatography was developed. The analytical range was 4–1200 g/g (in terms of the dry weight of a sediment). The procedure is based on the direct injection of acetone extracts of sediments into a chromatographic column. The detection limit was 5 ng/peak (signal-to-noise ratio of 3 : 1); the relative standard deviation was 5.6%. Errors introduced at particular stages of analysis and the total errors were evaluated for different sampling techniques. The results of determining elemental sulfur in the core samples of bottom sediments from Lake Baikal are presented.     

Application of chitosan and its derivatives for solid-phase extraction of metal and metalloid ions: a mini-review

Here we review chitosan-based materials for solid-phase extraction of metal and metalloid ions prior to their determination by atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry, mass spectrometry, and some other spectrometric techniques. We show that nearly zero affinity of chitosan and its derivatives to alkali and alkali-earth metal ions is very beneficial for separation of analytes from the salt matrix, which is always present in natural waters, waste streams, and geological samples and interferes with analytical signals. Applicability of chitosan to selective recovery of different metal and metalloid ions can be significantly improved via functionalization with N-, S-, and O-containing groups imparting chitosan with additional electron donor atoms and capability to form stable five- and six-membered chelate rings with metal ions. Among most promising materials for analytical preconcentration, we discussed chitosan-based composites; carboxyalkyl chitosans; chitosan derivatives containing residues of aminoacids, iminodiacetic acid, ethylenediaminetetraacetic and diethylenetriaminepentaacetic acids; chitosans modified with aliphatic and aromatic amines, heterocyclic fragments (pyridyl, imidazole), and crown ethers. We have shown that most chitosan derivatives provide only group selectivity toward metal ions; however, optimization of recovery conditions allows metals and metalloids speciation and efficient separation of noble and transition metal ions.     

A New Method for Producing a Nanosized γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Powder

A new method for producing a nanosized γ-Al₂O₃ powder was proposed, by which a saturated solution of aluminum oxychloride and sucrose was subjected to sequential heat treatment to 350°C to form a transient species and then to 800°C to form a nanosized γ-Al₂O₃ powder. The optimal treatment parameters were determined. Stages of the process were identified. The transient species and the nanosized γ-Al₂O₃ powder were studied.     

Polarization and spectral characteristics of anisotropic ring laser cavities with nonideal mirrors

A mathematical model for calculating the polarization and spectral characteristics of eigenmodes of nonplanar ring optical cavities with allowance for the phase anisotropy of oblique-incidence mirrors is described. The results of the numerical modeling and experimental measurements of the characteristics of laser mirrors and mode spectra of practically important four-mirror cavities with a nonplanar symmetric axial contour are compared. It is shown that the proposed mathematical model can be applied to optimal selection of lasers for laser cavities with allowance for their real parameters.     

Is Triphenylverdazyl an Indicator for Solvent-Separated Ion Pair?

The hypothesis implying complete capture of solvent-separated ion pairs by triphenylverdazyls used as internal indicators for unimolecular heterolysis of organic compounds was critically analyzed. Products of heterolysis of diphenylmethyl bromide in anhydrous acetonitrile in the presence of triphenylverdazyl were identified, and their distribution was determined. Alkylation of verdazyl under kinetic conditions almost does not occur, and verdazyl is consumed as a result of its reaction with hydrogen bromide liberated during the solvolysis.